A method of detecting a target molecule, the method comprising: forming a complex of a target molecule, a capture oligonucleotide, an oligonucleotide primer, and a single-stranded circular DNA; performing a nucleic acid amplification reaction by rolling circle amplification based on the formation of the complex; and detecting amplified nucleic acid; wherein the single-stranded circular DNA contains a first region, and a second region linked to the 3′-side of the first region, and preferably further contains a sequence complementary to a detection reagent-binding sequence; the primer contains a first aptamer sequence which binds to the target molecule, and a sequence which is linked to the 3′-side of the first aptamer sequence and is complementary to the first region of the single-stranded circular DNA; and the capture oligonucleotide contains a sequence complementary to the second region of the single-stranded circular DNA, and a second aptamer sequence which is linked to the 3′-side of the sequence complementary to the second region and binds to the target molecule.